How does Python's unittest library match patterns passed via the -p parameter?

I am running the following command to run only the tests located inside the file called test_CO2.py

python3.7 -m unittest discover -s some_path/tests/ -p "*CO2*"

My folder structure looks like the following:

some_path/tests/
  CO2
    test_CO2.py
  battery
    test_battery.py
  tank
    test_tank.py

I want to specify the tests that are ran. If for example I only wish to test the tank and CO2 code how can I do that? I thought of passing the following regex: \w*(CO2|tank)\w*.py which fails to find any tests.

I am thinking that the pattern passed in to the -p option does not accept regex. How, then can I specify the tests I wish to run?

I figured out how to bypass this restriction from unittest.

I can run specific tests with python3.7 -m unittest path_to_some_test

# take regex and find all files that match
# clean up results. i.e. remove './' from output
test_paths_result=()
test_paths=$(find . -regextype posix-extended -regex "${regex}")
for file_path in ${test_paths}; do
  # save clean results to array variable
  test_paths_result+=("${file_path:2}")
done

echo "Running test files that match the following expression: '${regex}'"
python3.7 -m unittest ${test_paths_result[@]}